The field of art to which this invention pertains is the maximization of middle distillate from heavy distillate hydrocarbon. More specifically, the invention relates to a process for the conversion of an aromatic-rich, distillable gas oil charge stock which is essentially free from asphaltenic hydrocarbons and possesses an aromatic hydrocarbon concentration greater than about 20 volume percent to selectively produce large quantities of high quality middle distillated while minimizing hydrogen consumption which process comprises the steps of: (a) reacting the charge stock with hydrogen, in a catalytic hydrocracking reaction zone, at hydrocracking conditions including a maximum catalyst bed temperature in the range of about 600.degree. F. (315.degree. C.) to about 850.degree. F. (454.degree. C.) selected to convert at least a portion of the charge stock to lower-boiling hydrocarbon products including middle distillate and to convert at least about 10 volume percent of the aromatic hydrocarbon compounds contained in the charge stock to provide an increased concentration of paraffin hydrocarbon compounds in the resulting hydrocracking reaction zone effluent; (b) separating the resulting hydrocracking reaction zone effluent to provide a middle distillate product stream and a paraffin-rich hydrocarbonaceous stream boiling at a temperature greater than about 700.degree. F. (c) recovering the middle distillate product stream; (d) reacting the paraffin-rich hydrocarbonaceous stream recovered in step (b) in a non-catalytic thermal reaction zone at mild thermal cracking conditions including an elevated temperature from about 700.degree. F. (371.degree. C.) to about 80.degree. F. a pressure from about 30 psig (207 kPa gauge) to about 1000 psig (6895 kPa gauge) and an equivalent residence time at 900.degree. F. (482.degree. C.) from about 1 to about 60 seconds to provide a non-catalytic thermal reaction zone effluent; and (e) separating the non-catalytic thermal reaction zone effluent to provide a fraction boiling in the range from about 300.degree. F. (149.degree. C.) to about 700.degree. F. (371.degree. C.)